Automatic telephone-exchange.



E., NEUHOLD.

AUTOMATIC TELEPHONE EXCHANGE. APPLICATION FILED APR. 2, 1910,

1,033,725. Patenfied July 23, 1912.-

UNITED STATES PATENT OFFICE.

ERWIN NEIl'I-IOLD, OF FBIEDENAU, NEAR BERLIN, GERMANY, ASSIGNOR TO THE FIRM OF DEUTSQHE TELEPHONWERKE M. B. H., OF BERLIN, GERMANY.

:- MIAU'IOMAYIIC. TELEPHONE-EXCHANGE.

Specification of Letters Patent.

Patented July 23, 1912.

Application filed April 2, 1910 Serial no. 553,075.

the mechanisms after the conclusion of a conversation.

According to the invention a common release conduc'tor for all the release magnets is formed from the separate testing lines of the series of selectors used through which each successive selector is indicated in the known manner as free or busy upon the -contact set of the previous selector. Thisis efl'ected bycausing. a resistance of 'sgitable magnitude to be inserted between t e oint at which the testing voltage is avai able for all the testing lines of the exchange (pole of the battery) and each sepa; rate testing line,"such insertion oc'currmg according to the system of busy test employed, t. e., whether the busy test is the absence or presence of a Working potentialeither in the firstcase upon the connection of the separate testing lines in the common conductor, orin the other case upon'the red vis on of the common conductor into Its parts. During the conversation the release magnets are either in the known manner all branched in parallel with each other fromv a common conductor or are in series with this conductor. v

The combination of the release conductor from its parts "according to the invention is for example'eflected at each selector -by its testing magnet, which responding in the known manner when the next free selector is found, brings the testing conductor of the latter into connection with the correspond- I ing testing conductor leading from the first named selector to the preceding selector,

and with its own releasing magnet, in such a way that when the testing magnet of another seeking selector isv'jo ned to the cons ductor, this magnet is put into a branch with the release magnets already connected and with the auxiliary resistance connected, which brancl 1according to the testing systemis supplied with, or deprived of suflicient current from the testing magnet. This is attained in substance by a suitable choice of the ohmic value of the auxiliary resistance relatively tothat of the release magnets on the one hand,'and that of the test ing magnets on the other hand. Ordinary (unpolarized) testing and release magnets or relays can be used without the testing condition of the connected or separate testing.lines being altered in any unsuitable way by the release magnets included and without the release magnets being influenced at an inappropriate time. Both of these conditions are important since otherwise double connections and premature releases would occur.

Upon the conclusion of a conversation the release. conductor receives current from a suitable source of potential through a relay or system of relays actuated by oneor both subscribers, by which means the selectors being restored to their position of rest the release. conductor is divided into its separate parts. According, to the'invention the release conductor is suitably made dependent upon a relay or system of relays which is always accessible to the calling subscriber,;z'. e., without the intervention of contacts closed in the selector--and, for example if so-called preselectors are not provided, is permanently connected with the This prevents the relay subscribers line. system beingremoved from the subscribers influence by failure of the contacts, and the series of selectors remaining wholly or partially incapable of'release, and further enables the release to be efi'ected at anytime independently of the particular. adjustment or time of running of the selector. By suitable arrangement of this relay system, moreover, which as the only one presenttransmits all operations of the. subscriber'to the selector, it is possible by means of a simple connection to the testing line to so modify "the circuits that not only the calling but also 4 the "called subscriber, and each .mdependentlyj of the other, can releaselthe' speaking connection. I, Q

; Theinventi'o n will be explained in greater loo 3c selector l.

,1; who is oined to his appropriate selector I detailwith reference to the accompanying drawing. This latter shows diagrammatically an exchange constructed according to the Well known Strowger system (see Electrotech'aische Zez'tschm'ft 1903, page 727), 6., the selectors each provided with a contact arm carrier-which can be raisedand turned, are divided into three groups which cooperat ng allow connections to be made between any two subscribersln a total number of say ten thousand subscribers, and of some one thousand such connections being i made simultaneously. 0t the first group (first group selectors l which contains ten thousand selectors each associated with a subscriber there are illustrated two selectors I and T ;'of the second group (second group selectors)which includes say three thou sand selectorsthere is illustrated one selector II; of thethird group ,(line selector) also with three thousand selectorseach having 100 subscriber,connections-one selector HT isfillustrated. The selector III is con- .nected to the contact sets-ofthe selector II and other selectors ll of this second rou 1 ,j by conductors 11, 12, 13, While the other selectors III of the third group are con- ".nected to'othercontacts'of the selector II.

In the same way the selectors II, TY and so forth are joincdto the contact sets of the The connection of a subscriber through conductors 5, 6' to a subscriber B who is joined through conductors 20, 21, or 17, 18 to three,corrcspondingcontacts of the selectors III and III, is effected either over the selectors I-'IIIII or I-IIIII or I LET-III- and so forth; the. selectors n+1? or IH-TII being sought out in the known way automatically so that each selector is only used for one speaking connec i tion'at a time.v The selector III towhich the desired subscriber B along with 99 other subscribers 1s CODIIGECtGClalS adjusted by the calling subscriber A with the aid of the magnets z and e of this selector to those contacts to which the lines 17,18 of the desired subscriber are joined.

The process of connecting, in detail is as follows: Suppose the number of the desired subscriber B is 5345. The "subscriber A first presses key 25 five times by which-means a-five-iold' current impulse passes from the battery a over conductor 15,'the left, hand" Winding of a difierential relay 4*, relay 1",

conductor. 5,1keyjt and earth. The relays .7"? and m attract their'arm'atu'res and-cause .911rrent .to. flowfrom'thebattery a over eonduetqr: 1-6, theright hand'armatures of,

.and 73 'conductorfiithe middle armature of ,the relay c which at firstis not yet excited,

theg-livackcontact "of. this armature, and the lifting magnet z of the selector 1 to earth, whichcurrent-results 1n. five successive excitations of s and a lifting of the switch.

shaft of five steps. Then the key t is pressed once by which means current passes from battery a over conductor 16, the right nected overthe conductors m, 7%,11) to the .selector II of the second group, This moving on of the contact arm is caused in the known manner by the establishment of a connection at the beginning of theturning movement of the switch'shaft between two springs p through the movement of a projection 0 secured upon the shaft-,this projection serving to hold the springs 10, apart when the switch shaft is in its position of rest. In consequence of this" contact at p the circuit or" the battery a is completed over an automatic interrupter S, the as yet unattracted armature k of the relay 2' and the turning magnet e. Consequently the-turning magnet 6 ,is' excited and moves on the arms I), c, at one step as often as the device 8 makes or breaks the circuit. If in this manner the arms I), c, d reach the contacts of conductors m, n, w and, it the selector H is not occupied with any other conversation,-

e. is in' its position of rest, a current flows from the battery as over the contact u-of the selector TI which is still closed, conductor w, arm (2 of I, the uppermost armature oi relay 2', its bank contact 43, the winding of relay i and earth back to battery a. The relay 2' attracts all its armatures and separates the turning magnet e from the interrupter S by raising the lowermost of the two'armatures it from its contact so that the magnet has no 4 current and the arms Z2, 0; (Z remain stationary; (2) separates the lifting and turning magnets z and e from the relay system 1*, 7' 1 z. e., from the conductors 84, 35; {3) connects the conductors 5, 6 (speakin lines) over two of the upper armatures 0L relay 2" to'the'contact arms 6, 0, and thus to the ;con-' 'ductorsm, a, andthe magnets e, a of the sec v 0nd group selector II, the relay z'oi? which is as yet unexcited. At'the same time the winding of relay 6 oil is connected through its armature 7a to a spring co1 1tactgactuated like the contact pand' over this contact to the battery a, so that the relayt reniains er cited solong as-the selector l'fis set, that is during the'periodot the conversation: The subscriber Af now presses the key t three times and the key 5 once, whereupon as described in connection with l,the litt- Iand finally as the result-of the operation of relay 2' the arms 6, 0, d are. brought upon the contacts of conductors 11, 12, 13 which lead to an unoccupied selector III,.the contact u of which is still closed.

In the present case two steps are necessary forthis. Atthe same time the conductorsm, a,

are disconnected-from the magnets e, z of select-or IIand joined over conductor 11, 12,

' to the magnets e, z of the selector III which has been foundunoccupied. Further when the switch shaft was raised the contact u of II was opened so that the testing line w belonging to selector II was deprived of current and this selector became indicated on the contacts of selectors I as busy.

Finally a relay, T hasbeen excited which simultaneously with excitation of the relay i of II deprives the testing line of selector III of current in order to prevent'this selector being brought into use by another party even before it has begun to move. (Such a relay could also be used for the selector II). The subscriber A now presses the key t four times and key t five times. By this means the lifting magnet a of III is excited four times and the turning magnet a five-times, so that the arms b, c, d ofselectouIII are moved on to the contacts of conductors 17, 18, 19 of subscriber B or No. 5345. On the'lifting of the switch shaft the contact at of III is broken and so the se ector III is henceforth indicated as busy upon the cont-act sets of the remaining *se: lectors, II, whereupon the hitherto excited relav T is deprived of current. If the subscriber B is not already occupied with another conversation the selector I belonging I to the subscriber B is in the position of rest and consequently the conductor 19 is connected with: battery a over the contact to of I, the armature and winding of the relay R, and the resting armature of the relay magnet 31 of I. As a result the relayz' of III is excited, whereupon (1) conductors ductors 17, 18 or the subscribers station B, ,(2) the magnets a, a of III are disconnected from the conductors 11, 12, and (3) the winding of the relay 2' of III is put permanent-ly in circuit over the contact q of-III. At the sametime the relay R of selector I is excited and disconnects itself from the l-cpnductor 19, connectingf eitself into a reta'ining current circuit extending over the armature of the corresponding release magnet 3 Through the conductor 19 being thus 1217, 18 for example by setting in action abell connected at the latter station between conductors 17, 18 or 20, 21", by means of a correspondingly connected magneto generator at station A. The speaking currents between the two stations run over the same set of conductors. The subscribers microphones are supplied from battery a, over the relay system r r 1* of the selector I. For this purpose the microphones may be considered as connected in known manner in parallel to the receivers between the conductors 5, 6, or 20, 21. The microphone supply currents" are too weak to cause any excitation of the relays r 1 even ifthey are'sutficiently strong for their purpose, In the sameeway the armature of relay r is not attracted because the two windings of 9' are equally strongly excited. During the process of connection described, the result of which is illustrated in the drawing-the release magnets 3 of selectors I, II, III have according to the invention, been connected in parallel, by means of the working contacts 4:4: on the uppermost armature of relay 2' and connections 40 and 41 of the same, to a conductor extending over the testing arm cl, which is made up of the separate testing lines w, 13, 19. This conductor can be supplied with currentover a connection 42 connections 37 and 38, will be explained later-through the relay system 1", 1' 1' of the calling subscriber, sothat, all the relays selectors which then, for example in the known manner "partly by means of springs and partly und the action of their weight,

return to the p sitionof rest. As a result (1) the contacts 2,1 are opened; (2) the relays 'i are deprived of current; (3) their respective armatures return to the position of rest, and (4) the contacts u are closed with the 'exceptionot-the contact u of I which, is only closed (by depriving therel'ayjRg-rof current) when the subscriber B alsohafi'g's up his receiver presses down his key? andso excites his release magnet y. In,this Way the system is brought back to directlyrthe other 6) over resistance 14.

Consequently ,both'o thewindings of relay 1 of selector e excited but not equally, and simultaneouslly the relays 1' and r are excited so thatal the relays attract their armatures, Current therefore fiows from the battery a, over; conductor 15, oiitei? the-position ofrestand the selectors II, III

gives the'working potential. At the instant II and I to earth.

thefree selector II is found, is too weak to excite the magnet. all the selectors can 'be equal so as always armatureof rfl'the two outer armatures of r and, rfiand the parallel connected release magnets, y to earth. In order that this method of release may be made possible without disturbance of the other functions of the testing line, the resistances 39 are according to the invention arranged upon the contacts a, and in the example of cone-- struction chosenfor illustration in whichthe potential of the testing line when busyis m'l so that the busy test is operated by the absence of the working potential, the arrangement is such that'when a selector is appropriated and set in action, the resistance 39 is disconnected from the testing line, while when the selector is in the position of rest, it lies between this conductor and the negative pole of the battery which mature release occur's'. In an analogous manner the resistance 39 of II can be so chosen that. the current flowing over this resistance in the magnet y'of selector I when The resistances 39 of to fulfil this-condition. Further according to the invention the ohmic resistance of 39- bears a definite ratio to theresistance of the testing magnets 2', namely such that if during the establishment of a speaking conmotion the contact arm of a selector, which is active in another speaking connection, comes upon the contact of the conductor to, 13, between which and earth all the release magnets are connected, current is so far withdrawn from the testing magnet 01 of that selector which is parallel to these releasing magnets by the eifect of resistance 39 inserted in the testing circuit, that that testing magnet does not respond and the other selector goes on to find a free conductor. In this way it is impossible for a ble connection to beestablished. 'x 'citation of the fife a in'agnets is as v described hy the llin subscriter, and

(Z of another selector should come for example upon the conductor w, no d1S21I13,I1 g6'= ment results since the release of the selecs 4 g I pplic'ation of the tall potential of the" battery through the relays 1"; 1, r of the: Y over thef j-connection14:2" to ftheco'nductor f If at this instant the contact arm -tor II not hindered by the selec- "tor is immediately available and may therefore ,beconnecte'd to-the calling selector If the connection 38 (and-correspondingly '37) is provided the contactu of the select r I can be brought into the position of rest.

by the subscriber A, bytherelease magnet 1 of the selector-I being eiicitedusimultaneously with the. other," release magnets overconductor 38. In this arrangement it is possible to disconnect the bridge of relays r 7, r at the selector I of thedesirerl 'sub- 1 scriber, by meansof a relayw excited simultaneously with the relay B, so that the whole speaking connection 5, 6.- 3 l, 35-m, a, 11, 1217, 18-20, 21, only contains a single bridge namely that of the relays .1, 1 r at selector I with the supply battery a, while otherwise two such bridges are present. The disconnection by the relay w is also advantageous in so far as by its means the relays r 1' of I are withdrawn from .the' influence of the calling current sent t-Otllf sub- ;scriber B, so that a false operation of the selector I is impossible. vThe connection 38,

37, has the further advantage thattlie called subscriber B can also release the speaking connection independently of thecalli-ng subscriber A, but otherwisefin the same {manner the latter. The relay a: may obviously not be present, the relay system 1, 1' r of the subscriber B remaining'in connection with him. .This release .titom both, ends makes it more certain that :the selectors will be released since each i'eleaselmagiiet can receive current from the two sides. T

The switching in of the release-conductor could naturally be effected from any other relay system, for example from -one first brought into action during 'tlieestablislr ment of the speaking connection, but the use of the relay placed immediately adjacent to the subscribers terminals, as described, has certain advantages which have already'been referred to. It is to'be noted that the automatic disconnection -of-the resistances (or relays) B ds-not absolutely necessary for there is nothing to prevent the release conductor being connected-through a resistance of suitable-dimensions with the releasing potential duringth'e conversation, a connection which, as described, comes into existence momentarily at every connection of one of the selectors II, III. p

In, a systemin which a selector is indicated as unoccupied, for'example, by a nil enft l and as busy byshine high'er poten t as s the case in the or ginal Stronger tern, tl e-flresistances are arranged, indicated at the selector II, that after the selector has been brought into use its test inglinetw) is connected over the auxiliary "resistance (39) .toffor example the earthing pointofthe battery (in. V'Iheiesting magnet i must then be joined to the-positive is the case in t 1e Strowger system-the se-- lector moves on so long as it is excited and or negative pole of the battery and must work in the op osite Way, 2'. e., so that-as comes to a standstill when current ceases to flow through it. In this case during the subscribers conversation not only the release magnets y but also the resistance 39 are inserted and the conductors 10-13 are connected to earth. Thus a premature release during the establishment of connections is prevented. On the other hand the testing magnet i of another calling selector, if it comes upon the conductor 'w- 13, always receives sutlicient current to respond over the parallel release magnets, care being taken through a suitable dimensioning of the resistance 39, that the component currents flowing through the separate release magnets, is not suilicient to excite these. The re? and adapted to connect a selector with the.

next free selector, a release magnet for each selector, connections between said release magnets and said separate testing circuits whereby the release magnets may be .branched parallel from a conmion circuit formed by the separate testing circuits, and a resistance lncluded in each separate testing circuit which is of such Value that current passing through the testing circuit will not operate the release magnet connected therewith.

' 2. An automatic telephone exchange system, comprising a source of current, a plu rality of .electromagnetically operated selectors, a relay system and conductors to convey current from said source to the selector magnets, a testing relay associated with each selector, forming part of a testing circuit and adapted to connect a selector with the next free selector, a-release magnet for each selector, connections between said release magnets and said testing circuits, whereby the release magnets may be branched parallel from a common circuit formed by the connected separate testing circuits, a resistance included in each separate testing circuit which is of such value that current passing through the testing circuit will not operate the release magnets connected therewith, a conductor connect-- ing the testing circuit with contacts of the said relay system, and electrical connections for simultaneously operating the connected release magnets.

3. An automatic telephone exchange system, comprising a source of current, a plurality of electromagnetically operated selec tors, a relay system and conductors to convey current from said source tov the selector magnets, a relay associated with each selector forming part of a testing circuit and adapted to connect a selector with the next free selector, a release magnet for each selector, connections between said release magnets and said testing'circuitswhereby therelease magnets may be branched paral lel from a common circuit formed by the connected separate testing circuits, a resistant: included in each separate testing circuit which 18 of such value that current passing through the testingcir'cuit will not tors, a relay system and conductors to convey current from said source to the selector magnets, a testing line adapted to be connected witheach selector, a testing relay associated with each selector to establish connection, between the testing line of a.

seeking selector andthe testing line of the selector found, a release-magnet for each 'selectorpineans for establishing connection between the testing line of the seeking selector and its corresponding release magnet, a resistance included in each separate testing circuit which is of such value that current passing through the testing circuit will not operate the release magnet connected therewith, connections between each release magnet and saidvtesting circuit whereby a common release conductor for all of the re lcasc magnets is formed, and means enabling either one or both,subscribers, each independently of the other, to operate simultaneously all of the connected release magnets.

lector and its corresponding release magnet,

means for disconnecting the testing magnet of the seeking selector from the testing line of the selector found, a resistance included in each separate. testing circuit which is of such value that current passing through the testing circuit will not operate the release magnet connected therewith.

d-An automatic telephone exchange system, comprising a source of current, a plurality '-"of electromagnetically operated sel ectors, a relay systemand conductors to convey current from said source to the selector magnets, a testing line adapted to be connected with each selector, a testing relay system associated with eachselector to establish connection between the testing line of a seeking selector and the testing line of the selector found, a release magnet for each selector, means for establishing connection between the testing'line of the-seeking selector magnets, a testing line adapted to be connected with each selector a testing relay associated with each selector to establish coniiectionbetween the testing line of a seeking 'selector and'the testing'lino of the selectorlfound, a release magnet for each se lectonf'ineansfor: establishing connection between the testing line of the seeking selector audits corresponding release magnet, means for disconnecting the testing magnet of the seekiiig selector from the testing line of thesele'ctor found, means for throwing into the testing circuits resistances so dimensioned with referen'cetothe testing magnets and release magnets that 'on the'one hand interference with the operation of another seeking selector is avoided,'and on the other hand theexcitationof the release magnetsis preso yentedu' Q 8. An automatic'telephone exchange system, comprising a source of current, a plu rality of electromagnetica-lly' operated selectors, a relay system-and conductors to 15 convey current from said source to. the sei lectormagnets, a relay associated with each selector and forming H art of a testing circuiti'a release magnet or each selector, connections between said release magnets and lthe'partsof said testing circuit whereby the release-magnets may be branched in parallel from a common circuit, and "a relay associated with eachselector which is so connected "as to become excited simultaneously with the excitation ofthe relay magnet of the preceding or seeking selector and to deprive the testing line of its corresponding selector of currentin order .to prevent this selector being brought into us by another party before it has begun its movement. v

9. An automatic telephone exchange system, comprising 'a source of current, a plurality of electromagnetically operated 'selectors, a relay system and conductors to convey current from said source tothe selectormagnets, a relay associated with each selector-and conductors to establish a testing circuit, a release magnet for each selector, connections between said release magnets and the parts of said testing circuit whereby the'release magnets may be branched in parallel from a common circuit, a resistance included in each separate testing CIICIllt which is of such valuethat current passing through the testing circuit will not operate the release magnet connected therewith, connections between each release magnet and said testing circuit whereby a common release conductor for all of the release magnets.

is formed, and a relay associated with each selector which is so connected as to become excited simultaneously with .ithe excitation of the relay magnet of thepreceding or seeking selector and to; deprive the .testing line. of its correspondingselector of current in order to preventthis selector being brought into use by another party before it has begun its movement.

10. An automatic telephone exchange system, comprising a source of current, a plurality of electromagnetically operated selectors, a relay system and conductors to convey current from said source to the selector magnets, a relay associated with each selector and conductors to establish a testing circuit, a release magnet for eachselector, connections between said release mag- 'nets-and said testing circuit whereby the re lease magnetsv may be branched in parallel from a common circuit, a resistance included in each separate testing circuit which isof such value that current passing through the testing circuit w'illnotv operate, the release magnet connected therewith, connections be- ,7

tween each release magnet and said testing circuit whereby a common release conductor for all of the release magnetsis formed,

means enabling either the eallin subscriber or the called subscriber and sec "independently of the other to. operate simultaneously all of the release magnets, a conductor con'- nected with said release magnets over said relay system, electrical connections for simultaneously operating all of the release magnets, and arelay associated with each selector which is so'connected asto become excited simultaneously. with" the excitation of the relay magnet of the precediii'g'jor' seekintg testing selector and toideprivel-thel line 0 its corresponding; ector of ,liiirrent,

tem, comprising a source of current, a plurality of electromagnetically operated se: lectors, a relay system and conductors to convey current from said source to the se lector magnets, a testin line adapted to be connected with each se ector, a testing re-.

lay associated with each selector to establish connection between the testing line of a seeking selector and the testing line of the selector found; a release magnet for each seleetor means for establishing connection'between the testing lineof the seeking selector and its corresponding release magnet, and a relay associated with each selector which is so connected as to become excited simultaneously with the excitation of the relay zfi magnet the preceding or seeking selector and to deprive the testing line of its corresponding selector of current in order to prevent this selector being brought into use by another party before it'has begun its movement. i

In testimony whereof, I have hereunto affixed my signature this 16th day of March 1910, in the presence oftwo Witnesses.

HENRY HAsPER, VOLDEMAR HAUPT.

Copies of this patent may be obtained for five cents eachfloy addressing the Commissioner of Patents,

. Washington D. G. 

